Isaac v



PATENTED JAN. 22, 1867. I V LYNN & G T SNOWDEN BALANCE SLIDE VALVE.

77252 ess 'es WM anni :am anni ffii,

ISAAC V. LYNN AND eEoRGn fr. sNoWDEN, oF PITTSBURG, PENNSYLVANIA. 'Leners Para: No. 61,441, dma January 22, 1867. I

IMPROVEMENT IN BALANGI: SLIDE-VALVES.

dlgs rlgehule'rcferr'sh tu in tigcse ittcrs ntcnt mit meltingpzut nf tlg: same.

TO ALL WHOM1 IT MAY CONCERN:

Beit known that we, GEORGE T. SN0WDE\\Y and SAAC'V. LYNN, of the city of Pittsburg, county of lle. I

gheny, and State 'of Pennsylvania, have invented certain new and'useful improvements in Balance Slide- .Yslves" for steam engines; and we do hereby declare that the following is a full and exact description thereof,

referencebeing had to the accompanying drawings Aand the let ters of' reference marked thereon.

The nature of. our invention consists in relieving the sliding-valvesof steam engines from'the pressure of steam upon the back of the valve by means of the mechanism hereinafter described.l

To enable others skilled in the art to make and use our invention, we will proceed to describe its construction and opera-tion. In the accompanying drawings- Figure 1 is a longitudinal section of our improved valve.

Figure 2.is a top view of the valvend its connections, cut thron'gh the line t, iig. 1.

Figure 3 is a perspective View of an' ordinary skeleton-valve, A, by itself.

The manner'in which we construct our valve is as follows: (as the valve-seat and its openings, the steam chest, and manner of connecting the valve-rod to the valve, are of the ordinary construction, and are well known to th'e skillful mechanic, it is therefore unnecessary to describe the same; we will therefore confine the description to our improvement and its necessary connections with the valve.)

The valve A, iig. 1, may be made in form as shown in iig. 3, or made as the ordinary valve, with the back faced o true, upon which rests the plate B, said plate having upon its upper sidethe short cylinder C; upon the under side of the steam-chest cover, R, is formed the short cylindcrf, which projects down into. the cylinder C, upon the plate B, and between the two cylinders is interposed the tapering ,packing-ring D, for the purpose of-making steam-tight joints'between the parts.' In fig. 2 the valve is shown by the dotted lines x, and t'will. be seen that -there will be `a downward pressure upon the valve equalto the pressure of steam upon` the area ofi surface indicated hy the points marked X, which should in all .casesbe` equal to the sum of the areas of the receiving openings, so that when steam isadmittedl into the cylinder by moving the' valve, the valve will notbe lifted from its seat by the pressure which then comes beneath it;l andas there are' two points in each revolution when both receiving openingsare covered by the valve, and both ends of the cylinder full-of steam (viz, just at the point of receiving and exhausting, which occur at the same time,) it will be seen that there is anupward pressure at these points equal to the pressure of steam upon the area of the receiving openings, and which should be counterhalanced by an equal pressure' from above in order to keep the valve upon its seat; it will, therefore, be found necessary in practice to make 4the area of surface indicated by the points X equal `to the area contained in both receiving openings, as above mentioned. By reference to iigs. l and 2 it willA be seen that there is an opening, ul, made through the plate B, for the 'purpose of conducting into the exhaust opening 0,. `any steam that may leak through thejoints between the cylinders C andf, and may be large or small, as may seem best in thejudgment of the mechanic. If an ordinary valve, closed on ,the back, is used, instead of the skeleton-valve shown in gs. 1 and 3, the steam which muy leak through the joints may be taken down through l said valve by drilling one or two small holes in it, which may be stopped up in cusc any of the parts'above th'e valve become inoperative, in which event the parts can be removedand thc valve used as an ordinaryfvalvie until I such parts can be repaired. The packing-ring D, shown in iig. l, may either bc made straight op the outside' o1' convex, as shown by the dotted lines h, to allow the plate B to adjust itself upon the valve A. ,inhncase the steam-chest cover R should be screwed down more on onesidc than the other; we therefore do notI 'confine ourselves to any one of the methods, for either may be used as circumstances may require. f

In using our improved valve, steam is admitted into the steam chest, and from thence to and from thccylin- :der in t'he usual manner by the movement of the valve A, sn-id valve requiring less power to move .it thun is msually employed where the full pressure of steam comes upon the back of the valve.'

Having thus described the nature, construct-ion, and operntiu of our improvement in balance slide-valves, what we claim as of our invention, is l, The packing-ring D, or its equivalent, when used in combination with the cylindersf and C, plate B, and vaive A, constructed, ai'ranged, and operating substantially as herein described, and fo'r the purpose set forth.

ISAAC V. LYNN, GEORGE T. SNOWDEN.

Witnesses:

W. D. BAKER, (JAMES McBnms. 

